Regional variation of cell proliferation within the facial processes of the chick embryo: a study of the role of ‘merging’ during development

Development ◽  
1980 ◽  
Vol 57 (1) ◽  
pp. 37-49
Author(s):  
Robert Minkoff

Variation in rates of cell proliferation along the long axis of the maxillary process, within the lateral nasal process and in the zone of attachment between these structures was analyzed employing DNA labeling indices. Chick embryos were labeled with [3H]thymidine for 1 h and processed for histology and autoradiography. The percentage of labeled mesenchymal cellswas determined in delineated areas. Analysis of labeling indices indicated that rates of cell proliferation varied withineach of the facial processes. Regions where rates of proliferation were maintained at elevated levels were the boundary areas of the facial processes (e.g. the anterior tip of the maxillary process) and the zones of attachment between the facial processes (e.g. between the maxillary process and the lateral nasal process). Despite the presence of elevated rates of proliferation in selected regions within the facial processes, however, the percentage of labeled cells in all areas declined with advancing developmental age. These findings support the hypothesis, proposed by Streeter and Patten, that the ‘merging’ of adjacent facial primordia, such as the maxillary and lateral nasal processes, is accomplished by elevated rates of cell proliferation within the zones of attachment compared to the rates of proliferation in adjacent regions.

Development ◽  
1977 ◽  
Vol 40 (1) ◽  
pp. 101-113
Author(s):  
Robert Minkoff ◽  
Amy J. Kuntz

The role of cell proliferation was analyzed in the chick embryo system employing DNA labeling indices during the invagination of the olfactory placode and the development of the lateral and medial nasal processes. Chick embryos were labeled for 1 h with [3H]thymidine and processed histologically and autoradiographically. The percentage of labeled mesenchymal cells in delineated areas within and adjacent to the nasal processes was determined. From analysis of labeling indices of each area at successive developmental stages, it was concluded that cell proliferation of mesenchyme, as measured by DNA labeling indices, did not appear to increase during the formation of the nasal processes, and that cell proliferation actually declined during the later stages of nasal process formation. Differences were also found between the labeling indices of the mesenchyme of the nasal processes as compared to that of adjacent areas. These differences tended to become greater as development progressed. In all of the areas studied, cell proliferation declined during the later stages of development but the magnitude of the decline was greater in the areas adjacent to the nasal processes. Differential rates of decline, rather than acceleration of cell proliferation, therefore, appears to be operative as a morphogenetic mechanism during early primary palate formation.


Development ◽  
1985 ◽  
Vol 88 (1) ◽  
pp. 25-37
Author(s):  
Maarten Van De Kamp ◽  
S. Robert Hilfer

The role of cell proliferation in the formation of scleral ectomesenchymal condensations underlying the conjunctival papillae was examined with in vivo tritiated thymidine labelling in chick embryos ranging in age from 8 days 0 h to 10 days 12 h. Percentages of labelled nuclei were determined in both ectomesenchyme and the deeper fibrous sclera for short-term and continuous tritiated thymidine incubations. During formation of the ectomesenchymal condensations the percentages of labelled nuclei were consistently higher within the condensations than in corresponding non-condensing ectomesenchyme between papillae. The consistent differences of labelling percentages observed within the condensing versus noncondensing ectomesenchyme were not found in the fibrous sclera at any stage. All areas of both the ectomesenchyme and fibrous sclera showed decreases in the percentages of labelled nuclei from 8 days Oh to 10 days 12h, although the decline in the ectomesenchymal condensations beneath papillae occurred more slowly than in areas between papillae. The data suggest that the conjunctival papillae directly influence the proliferation in the subjacent condensing ectomesenchyme but have no effect on the ectomesenchyme between papillae or any region of the deeper fibrous sclera. The observations of this investigation are discussed in relation to other studies of the development of the pre-ossicular mesenchyme.


1984 ◽  
Vol 224 (3) ◽  
pp. 769-777 ◽  
Author(s):  
A Ferioli ◽  
C Harvey ◽  
F De Matteis

The ability of drugs to cause uroporphyria in hepatocytes from 17-day-old chick embryos has been investigated and the response of the cells in culture compared with that of the intact liver of the embryos in ovo. In this chick-embryo system, drugs that cause accumulation of uroporphyrin within 19-24 h can only do so in culture; in contrast, 2-allyl-2-isopropylacetamide and 3,5-diethoxycarbonyl-1,4-dihydrocollidine, which stimulate production of protoporphyrin, are effective both in culture and in ovo. A role of exogenous iron in worsening drug-induced uroporphyria was demonstrated in cultures of hepatocytes; iron also caused preferential accumulation of uroporphyrin from added 5-aminolaevulinate in the absence of a porphyrogenic chemical. Uroporphyria was induced in cultures of hepatocytes by drugs of widely different structures, suggesting that the primary molecular target with which they interact may be relatively aspecific in its binding characteristics. These results are briefly discussed, and two alternative hypotheses for the drug-induced effect in uroporphyrinogen metabolism are considered.


2015 ◽  
Vol 26 (5) ◽  
pp. 978-992 ◽  
Author(s):  
Guang Wang ◽  
Yan Li ◽  
Xiao-Yu Wang ◽  
Manli Chuai ◽  
John Yeuk-Hon Chan ◽  
...  

This is the first study of the role of BRE in embryonic development using early chick embryos. BRE is expressed in the developing neural tube, neural crest cells, and somites. BRE thus plays an important role in regulating neurogenesis and indirectly somitogenesis during early chick embryo development.


Development ◽  
1978 ◽  
Vol 46 (1) ◽  
pp. 65-74
Author(s):  
Robert Minkoff ◽  
Amy J. Kuntz

Cell proliferation, as measured by DNA labeling indices was analyzed during the early development of the maxillary process. Chick embryos were labeled with [3H]thymidine for .1 h and processed for autoradiography. The percentage of labeled mesenchymal cells was determined within delineated areas in the maxillary processes and in adjacent regions. Analysis of labeling indices in each of the areas at successive stages of development demonstrated a pattern of declining rates of cell proliferation with advancing developmental age. Cell proliferation in adjacent regions declined earlier and, in some instances, faster than it did in the maxillary process. Cell density was measured in the maxillary process and the roof of the stomodeum and was found to be higher in the maxillary process throughout the period studied. Cell density and cell proliferation data were analyzed with reference to the operation of ‘density-dependent inhibition’ of growth as a regulatory mechanism for the observed changes. ‘Density-dependent inhibition’ of growth was not a satisfactory explanation for the observed differences between the maxillary process and adjacent regions.


1980 ◽  
Vol 85 (1) ◽  
pp. 171-185 ◽  
Author(s):  
K. G. BAIMBRIDGE ◽  
T. G. TAYLOR

SUMMARY A radioimmunoassay for chicken calcitonin (CT) was used to study changes in the normal levels of CT in the circulation of chick embryos during incubation and in hatched chicks. The hormone was detectable in embryos whenever the plasma concentration of calcium was greater than 2·5 mmol/l. The level of CT at the time of 'pipping' was exceptionally high but when pipping was artificially advanced or retarded the peak of CT was dissociated from the physiological event of pipping. When embryos were injected with calcium, CT secretion was stimulated but the maximum level induced was substantially less than the normal peak level observed at pipping although an extreme degree of hypercalcaemia developed. When CT was removed from the embryonic circulation by injecting anti-CT plasma, a mild but statistically significant hypercalcaemia developed and in another experiment exogenous CT significantly decreased an artificially induced hypercalcaemia. The β-antagonist, propranolol, decreased and the β-agonist, isoprenaline, increased concentrations of CT in the circulation. We suggest that the role of CT in the chick embryo may be to restrict the hypercalcaemia resulting from the large movement of calcium from the eggshell to the developing embryo and its yolk-sac and that one of the natural stimuli for the release of CT in the late stages of incubation could be β-adrenergic.


2019 ◽  
Author(s):  
Alireza Sepehri

BACKGROUND Nonlinear electromagnetic waves give us the best opportunity to explore evolutions of cells in biological systems. These waves carry important information about the status and various stages of life and death of a cell in these systems. In fact, cells send their information to other cells by exchanging non-linear fields. In this research, we will use of nonlinear waves for considering the role of initial DNAs in process of formation of the little brain and neural circuits in a chick embryo. Also, these nonlinear waves give us the best opportunity to explore the role of the little brain in voluntary actions in absence of the main brain in a bird. Some of these waves play the role of signal of death and lead to the stop of exchaning information between cells and end the life. The origin of these waves is also one of subjects in our consideration. OBJECTIVE There are no objective METHODS 1.We provide a system of shell-less culture from fertilized eggs. We creack eggshell and transform the whole egg contents to culture vessel. The culture vessels are maintained at $38^{0}C$ and rotated with 120° clockwise twice a day. After 54 h, in most of vessels, chick embryo is emerged. We connect these chick embryos (ex-ovo) to an scope and consider evolutions of nonlinear waves. We analyze evolutions of radiated waves of these embryos before and during formation of head. Then, to consider exchanging information between initial DNAs, we put two systems of chick embryos in an inductor and send a current to it. We consider changes in output currents and compare them with input currents. 2. First, we connect hearts of some birds to an scope and remove their head eventually. We analyze exchanged signals between the little brain on the heart and other parts of body. Then, we removed heads of some birds suddenly and consider radiated signals of the little brain again. This helps us to explore the origin of signal of death in a biological system. RESULTS We have four observational results 1.Before formation of brain, the little brain is formed on the heart. This little brain send it's information to other cells by exchanging waves with them. We can observe these waves on the scope. 2. After a period of time, the main brain interior of head is formed and interact with the little brain on the heart. This leads to an increase in observed radiated waves on the scopes. 3. If we put two shell less culture systems of chick embryos in an inductor and send an input currents to it, a magnetic field is emerged that interact with little brains of two systems. Exchanged waves between two little brains change magnetic field and input currents. 4. When, head of a bird is removed eventually,some signals of death exchange between brain on the head and the little brain on the heart and life is ended. However, by cutting heads suddenly, the interaction between head and little brain is stoped and these signals coulnt play any role. CONCLUSIONS In this research, we find that after formation of initial DNAs of chick embryo, they exchange electromagnetic signals with medium and each other. In fact, each gene of these DNAs act like the reciever or sender of radio waves. To control the process of transferring information, some circuits are emerged that each circuit depends on the activity of one gene. Because of various types of emitted waves, each neuron has several types of terminals in dendrite and axon to receive and send these waves. Before formation of neurons, initial informations are transmitted by blood molecules. Because of the role of blood molecules in transferring initial information, first circuits are formed on the heart and build the little brain . However, eventually, some circuits are emerged on the head which construct the brain. We bring some reasons for the existence of the little brain. We connect a chick embryo to an scope and observe evolutions of waves during formation of the little brain and the main brain. In absence of brain, the little brain emit some signals, while by passing time and formation of brain, the interaction between these systems leads to an increase in radiated waves. Then, we put two shell-less cultures of chick embryos in an inductor, apply a magnetic field to both of them and show that little brains of these systems interact with each other and change the value of output magnetic field and currents. Next, we consider signals of the little brain of the birds during removing their heads. We find that always, brain send some signals to the little brain and inform it of the end of life. However, if removing is done suddenly, these waves couldnt be exchanged and heart continue to work. This produce some hopes to cure patients.


1990 ◽  
Vol 269 (2) ◽  
pp. 437-441 ◽  
Author(s):  
R W Lambrecht ◽  
J M Jacobs ◽  
P R Sinclair ◽  
J F Sinclair

It was previously shown that uroporphyrinogen oxidation is catalysed by a form of cytochrome P-450 induced by 3-methylcholanthrene [Sinclair, Lambrecht & Sinclair (1987) Biochem. Biophys. Res. Commun. 146, 1324-1329]. We have now measured uroporphyrinogen oxidation and uroporphyrinogen decarboxylation simultaneously in 10,000 g supernatants from the livers of methylcholanthrene-treated mice and chick embryos incubated with an NADPH-generating system. We found that uroporphyrinogen oxidation is associated with inhibition of uroporphyrinogen decarboxylase activity. The decreased uroporphyrinogen decarboxylase activity was not due to depletion of substrate, since decarboxylase activity was not increased by a 2.6-fold increase in uroporphyrinogen. Uroporphyrinogen oxidation and the associated inhibition of decarboxylase activity were also observed with liver supernatant from methylcholanthrene-treated chick embryo; both actions required the addition of 3,3′,4,4′-tetrachlorobiphenyl. Uroporphyrinogen oxidation catalysed by microsomes from a methylcholanthrene-treated mouse inhibited the uroporphyrinogen decarboxylase activity in the 100,000 g supernatant. Ketoconazole, an inhibitor of cytochrome P-450, prevented both uroporphyrinogen oxidation and the inhibition of uroporphyrinogen decarboxylation. The addition of ketoconazole to mouse supernatant actively oxidizing uroporphyrinogen inhibited the oxidation and restored decarboxylation. The latter finding suggested that a labile inhibitor was formed during the oxidation. These results suggest uroporphyrinogen oxidation may be important in the mechanism of chemically induced uroporphyria.


1981 ◽  
Vol 198 (2) ◽  
pp. 321-329 ◽  
Author(s):  
U Giger ◽  
U A Meyer

The role of haem synthesis during induction of hepatic cytochrome P-450 haemoproteins was studied in chick embryo in ovo and in chick embryos hepatocytes cultured under chemically defined conditions. 1. Phenobarbitone caused a prompt increase in the activity of 5-aminolaevulinate synthase, the rate-limiting enzyme of haem biosynthesis, and in the concentration of cytochrome P-450. This induction response occurred without measurable initial destruction of the haem moiety of cytochrome P-450. 2. When intracellular haem availability was enhanced by exogenous haem or 5-aminolaevulinate, phenobarbitone-medicated induction of cytochrome P-450 was not affected in spite of the well known repression of 5-aminolaevulinate synthase by haem. These data are consistent with the concept that haem does not regulate the synthesis of cytochrome P-450 haemoproteins. 3. Acetate inhibited haem biosynthesis at the level of 5-aminolaevulinate formation. When intracellular haem availability was diminished by treatment with acetate, phenobarbitone-medicated induction was decreased. 4. This inhibitory effect of acetate on cytochrome P-450 induction was reversed by exogenous haem or its precursor 5-aminolaevulinate. These data suggest that inhibition of haem biosynthesis does not decrease synthesis of apo-cytochrome P-450. Moreover, they indicate that exogenous haem can be incorporated into newly formed aop-cytochrome P-450.


Development ◽  
1969 ◽  
Vol 22 (3) ◽  
pp. 349-371
Author(s):  
P. D. F. Murray ◽  
Daniel B. Drachman

Skeletal muscle contractions are necessary during embryonic life for the normal development of joints. The general features of joint development in immobile limbs were first studied with the techniques of grafting and organ culture. (Murray, 1926; Murray & Selby, 1930; Fell, 1925; Fell & Canti, 1934; Hamburger & Waugh, 1940; Lelkes, 1958). However, these methods of necessity entail a drastic alteration in the environment of the developing articulations, which may result in gross distortions of the skeletal structures themselves. More recently, neuromuscular blocking agents have been used to produce paralysis of chick embryos in ovo. When administered intravenously, these pharmacological substances produce profound paralysis, which may be continued for prolonged periods during embryonic development (Drachman & Coulombre, 1962a, b). Drachman & Sokoloff (1966) have analyzed the primary development of the knee, ankle and toe joints of the chick embryo by the use of these methods.


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